#include <stdio.h>

int  main()
{
	int i = 0;
	double num = 0;
	int n = 0;
	scanf("%d",&n);
	for(i = 1;i <= n ; i++)
	{
		 num += (1.0/i);
	}
	printf("%.6lf",num);
	return 0; 
}
